There are many well established advantages of counterbalanced canopy-type closure members, such as garage doors, which advantages include simplicity of installation and operation, easy opening and closing, absence of complicated space consuming support structure, and the automatic weather shield provided by the door when in an open position. However, the usual construction of these doors also gives rise to certain structural and operational problems which have prevented doors of this type from operating in the most desirable manner.
One of the primary problems confronted by designers of one-piece canopy doors has been the difficulty of providing a door having the desired strength and stiffness while at the same time being of light weight. Inasmuch as the magnitude of the counterbalance mass as disposed adjacent the upper edge of the door increases at the greater rate in proportion to any increase in the structural weight of the door, known canopy-type doors have accordingly not possessed the desired strength in view of the necessity of maintaining a minimum door weight. Many of these known canopy-type doors have thus been unable to withstand large panel loads thereon, such as caused by heavy winds which often exist in hurricane areas. However, this sacrifice in door strength was believed necessary in order to maintain the door weight at an acceptable magnitude. This lack of door strength has, however, greatly restricted the geographical utilization of doors of this type, and has also made these doors more subject to warpage.
Known canopy-type doors also are somewhat difficult to move into a fully closed position, particularly if a motor-driven operator is not utilized. When the door closely approaches its closed vertical position, the counterweight is located substantially directly above the hinge axis, while the weight of the door is effectively located below the hinge axis. Thus, there is very little unbalanced weight which is effective for urging the door into its fully closed position. Such doors will thus often reach a location which, while closely adjacent the fully closed position, will nevertheless be slightly spaced therefrom. Also, in these known doors, the counterweight does not provide a material force in the closing direction for holding the door in its closed position. Further, there was no provision for adjustment in the counterweight or the position of the hinge axis relative thereto in order to adapt the door to variations in the vertical dimension of the door opening, which adjustments could be made at the job site.
Another disadvantage of known one-piece canopy-type doors is the rather large structural rail members which are normally provided along the lower edge of the door to provide the necessary strength against bowing or warping. This heavy structural rail member along the lower edge of the door was believed necessary in order to transmit the panel loads to the side members. Further, when doors of greater width were desired, such as a double-width door, then the weight and size of this bottom rail member was still further increased. Additional trussing was also often added to the door, thereby resulting in an extremely heavy door having substantial weight adjacent the bottom edge thereof in widely spaced relation from the hinge axis. This thus creates a very undesirable weight factor and accordingly requires the use of an extremely large counterweight mass.
A further disadvantage in known one-piece canopy-type doors is the problem caused by the collection of rain and snow on the top of the door when in an open position. Most known doors of this type do not possess adequate structure for permitting proper drainage of water, whereby substantial quantities of water tend to collect on the opened door. This substantially effects the balance of the door and, when the door is closed, causes the door to close much faster than desired. This can cause injury to the person operating the door, and can also result in water being dumped onto the operator.
Thus, it is an object of the present invention to provide an improved, one-piece, counterbalanced canopy-type closure member, particularly a garage door construction, which substantially overcomes the above-mentioned disadvantages.
More particularly, it is an object of the present invention to provide:
1. An improved door construction, as aforesaid, which utilizes an improved counterbalance container fixedly secured to the door along the upper edge thereof, which container is of smaller cross-section to permit a counterbalance mass to be raised relative to the hinge axis without increasing the vertical height of the door so as to permit a substantial reduction in the counterbalance mass without any effective decreasing in the counterbalance moment.
2. A door construction, as aforesaid, wherein the counterbalance container and part of the mass therein projects outwardly a slight distance beyond the front face of the door to create a counterbalance moment which, when the door is closely adjacent its vertical closed position, urges the door into its closed position.
3. A door construction, as aforesaid, which has the hinge axis carried by heavy support plates fixed to and extending downwardly from the opposite ends of the counterbalance container to provide substantially increased strength and rigidity, while permitting the door to be of minimum weight.
4. A door construction, as aforesaid, having an improved side rail structure which eliminates the need to notch the ends of the face panels to be inserted into a channel-like tie member, which structure also eliminates the need for caulking by permitting the edges of the face panels to be inserted against a resilient weatherstrip positioned in the bottom of the channel-like member.
5. A door construction, as aforesaid, which utilizes one or more, and preferably at least two, vertical load-carrying channels disposed between and substantially parallel to the side rails, which channels at their upper ends are fixedly connected to the counterweight container and project downwardly therefrom as a cantilevered beam. These vertical channels permit the loads as imposed on the door panel to be transmitted from the bottom to the top thereof, so that the bottom rail can be of mimimum size and weight, while at the same time substantially heavy loads (for example, hurricane winds) can be imposed on the door panel since the door effectively acts as a cantilevered beam which is fixed to and projects downwardly from the counterweight container.
6. A door construction, as aforesaid, wherein the side rails and the vertical channels are each of a tapered decreasing cross-section as they project away from the counterweight container so that the door strength progressively decreases toward the lower free edge of the door to result in the door having optimum strength yet minimum weight. More importantly, this tapered structure minimizes the weight which is located furthest from the hinge axis so that the size of the counterbalance mass can be minimized.
7. A door construction, as aforesaid, wherein drainage channels are provided along the opposite sides of the door for permitting the water which tends to collect on the top of the opened door to be drained to the front edge of the door for discharge exteriorly of the building, whereby the build-up of water on the door is effectively prevented.
8. A door construction, as aforesaid, which while normally designed as an eight foot wide door, can also be used as a sixteen foot wide door by removing the adjacent side rails from two eight foot doors and replacing same by vertical channels, which vertical channels are then secured together, thereby resulting in a wide door having the desired strength and rigidity. This structure, also decreases the problem of transporting the door, while at the same time permits an efficient and inexpensive assembly of the wide door at the job site.